In a conventional internal combustion engine for an automobile, each cylinder is provided with one fuel injection valve. In such a conventional engine, the same number of fuel injection valves as the number of the cylinders are mounted to a fuel supply pipe device, which supplies fuel to the fuel injection valves. In recent years, for example, JP-A-2005-220875 and JP-A-2006-125333 propose a twin injection engine, in which two fuel injection valves are provided respectively to two intake valves in each cylinder. In the present structure, two fuel injection valves are provided in each cylinder, and therefore the number of the fuel injection valves, which need to be mounted to a common fuel delivery pipe of the fuel supply pipe device, becomes twice, compared with the conventional engine in which one fuel injection valve is provided in each cylinder. Furthermore, in the twin injection engine, two adjacent fuel injection valves in each cylinder are significantly close to each other. Accordingly, a mounting work of the fuel injection valves to the fuel delivery pipe, an exchanging work of the fuel injection valves in a case of malfunction, and electric wiring to the fuel injection valves are difficult in the twin injection engine. In addition, since the number of the fuel injection valves mounted to the fuel delivery pipe becomes twice, load exerted to the fuel delivery pipe increases, and therefore mountability of the fuel delivery pipe to the internal combustion engine may be impaired. In addition, pulsation may be significantly caused in fuel supplied from the fuel delivery pipe to the fuel injection valve, and therefore fuel supply and fuel injection may become unstable.
For example, in a conventional fuel injection device of JP-A-2006-125333, fuel supplied from a fuel pump is accumulated in a delivery pipe, and the fuel is supplied from the delivery pipe and injected from injectors in an internal combustion engine. A cylinder head of a multi-cylinder internal combustion engines is provided with injectors. More specifically, two injectors are provided in each cylinder, and all the injectors are connected to a fuel passage, which is one inner space, in the delivery pipe. In the fuel injection device of JP-A-2005-220875, two injectors are provided to one throttle body of an engine. The delivery pipe includes a first pipe, to which one of the two injectors is connected, a second pipe, to which the other of the two injectors is connected, and a communication pipe, which communicates both the first and second pipes with each other. Fuel is supplied from a fuel pump, and the fuel flows from the first pipe through the communication pipe into the second pipe. In the fuel injection device of JP-A-2006-125333, all the injectors are connected to the one inner space of the delivery pipe. In addition, two injectors are synchronously manipulated in response to its closing operation, and accordingly pulsations are caused at two locations in the delivery pipe. Thus, the pulsations interfere with each other to be amplified in the delivery pipe. As a result, quantity of fuel injected from injectors becomes unstable. In the fuel injection device of JP-A-2005-220875, the fuel supply pipe device including the two delivery pipes and the communication pipe has the one common inner space. Therefore, pulsation is amplified in the one common inner space inside the fuel supply pipe device, and consequently quantity of fuel injected from each of the injectors becomes unstable. Furthermore, the fuel injection device of JP-A-2005-220875 includes the two delivery pipes and the communication pipe, and therefore the structure is complicated and increased in size.